In this blog post, we will look at how altruistic behavior evolved in humans, focusing on the selfishness of genes and the repetition-reciprocity hypothesis.
If we assume that the total history of the Earth is 4 billion years, the history of humankind is only 1 minute. However, even if it is only one minute in a day, that one minute is a long period of time, equivalent to about 1 million years. Humankind has existed on Earth for this long time and has evolved alongside various animals. The study of how organisms, including humans, have evolved is one of the most important tasks in modern biology.
One of the most widely known theories of evolution is Richard Dawkins’ The Selfish Gene. This theory suggests that all evolutionary phenomena can be understood from the perspective of “genes” and that organisms behave in ways that are most effective for spreading their genes, rather than themselves.
Take worker bees, for example.
Worker bees are unable to reproduce and spend their entire lives working for the queen bee. On the surface, this seems like an extremely altruistic behavior. However, Dawkins explains this from the perspective of genes. Since worker bees and queen bees share the same genes, the behavior of worker bees in helping the queen bee survive and reproduce ultimately benefits the spread of their own genes. In other words, even altruistic behavior is part of the “selfish” strategy of genes.
In this way, Dawkins’ theory provides a convincing explanation for altruistic behavior between relatives. However, there are clear limitations to this theory. Humans often behave kindly toward people who are not related to them. For example, we give directions to strangers we have never met before or carry someone’s bags for them. Such altruistic behavior between non-relatives cannot be fully explained by the “selfish gene” theory alone.
Another theory that emerged to compensate for this limitation is the “repetition-reciprocity hypothesis.” This hypothesis states that the longer a relationship with another person must be maintained, the more likely it is that altruistic behavior will occur, because doing something nice for someone now will result in something nice in return in the future.
In other words, altruism can evolve in relationships where mutual benefits can be expected. A representative example of this theory can be found in the social behavior of chimpanzees. If chimpanzee A carefully grooms chimpanzee B, B is more likely to share food with A in the future.
However, if A grooms B and then immediately asks for food, B is likely to refuse. This is a strategy similar to the commonly known principle of “tit for tat,” which means, “If you do something nice for me first, I will do something nice for you. But if you don’t do anything nice for me, I have no reason to help you.”
Another interesting example can be found among vampire bats. Despite not being related, they exhibit altruistic behavior. On days when they have successfully hunted and obtained enough blood, vampire bats share their blood with their companions who have not been able to find any. This is not simply kindness, but behavior that expects a “future reward” in the form of help from others when they are unable to obtain blood themselves. According to actual research, if bat A shares its blood with B, the probability that B will help A when A is in trouble is statistically significantly higher.
However, the repetition-reciprocity theory is not a perfect explanatory system. This theory requires two premises for altruistic behavior to occur. The first is the continuity of the relationship. In other words, the two individuals who have formed an altruistic relationship must meet repeatedly. If the relationship is one-time, there is no reason to do a favor for the other person because there is no need to worry about retaliation.
Consider, for example, the culture of tipping. When a foreign traveler visits a restaurant, the likelihood of them returning to that restaurant is very low. So, is there really a need to tip? If there is no possibility of a repeat encounter, then theoretically there is no need to tip. However, in reality, most travelers leave a tip. This shows that the theory of repetition and reciprocity does not work perfectly in one-time relationships.
In other words, the repetition-reciprocity theory is valid under the assumption that altruistic behavior is advantageous in repeated relationships. However, the scope of the theory is limited when it comes to explaining altruism in one-time relationships. As such, human society consists of both repeated relationships and frequent one-time encounters, so another complementary theory is needed to explain the origin of altruism.
Nevertheless, most social relationships are based on repetition rather than one-time encounters. Friends, family, coworkers, and local communities are all relationships based on long-term interactions. Therefore, the repetition-reciprocity theory provides a very useful framework for explaining many altruistic behaviors observed in real life.
In conclusion, the repetition-reciprocity hypothesis plays an important role in understanding how altruistic behavior could have evolved.
However, this hypothesis cannot explain all altruism, as it has limitations when applied to one-time relationships. Therefore, in order to explain altruism in humans and animals more comprehensively, factors such as direct rewards, indirect benefits, reputation effects, emotional satisfaction, and morality must also be considered in addition to the repetition-reciprocity theory.
